S2 aby rough running, cutting out, black smoke help!!

[Cossie7]

Right boys I know I've had a similar post up before but was a bit off track and I've done loads since then lol

I'll try and explain but bear with me, when driving the car was originally bogging down spluttering and kicking black smoke out while trying to build boost so since then I've. ..

Checked for boost leaks
Fitted new plugs
Tfsi coil pack conversion
New icv
New mfts
New temp sensor on the rear of the head
Cleaned maf connections
Checked for vacuum leaks
Checked maf hose

Today I decided to use the car all day today and at first was running OK "ish" still farting about when building boost but no more than normal then all of a sudden for about an hour the car ran as sweet as a nut full boost etc with no problems. GREAT I thought until I was waiting at the school for the bairn with the car ticking over and I actually heard the engine note change from a purr back to spluttery like it was on 4.75 cylinders but not lol and it has been like this since.
.
After that I had to drop people off at the train station at rush hour and things got much worse it started hunting and cutting out constantly also when trying to pull away it would just black smoke and sound like it was trying to build boost from around 1250rpm ie turbo could be heard starting to try and spool and I was having to dip clutch to get it to rev up just to get it to move!!

Another strange thing I noticed as when I was in the traffic I noticed the outside temp gauge stating 45 degrees so I can only assume it's under the bonnet somewhere as it Def wasn't that hot in sunny Newcastle lol and it was at it's peak of pissing me off by this point. But anyways once I'd dropped them off and got out the traffic the temp gauge dropped back to 17 and the car ran much better instantly.

I may be wrong but this leads me to think something electronic doesn't like being warm and it's acting itself ? But what could it be?

Sorry for the long winded post but just trying to give as much info as possible.

Any help would be great as I'm near the end of my tether with it now like lol.

[Big Lee M]

It sounds like a bad boost leak, but when.you say temp related I'd point to the coils. But then you say you've changed them.for tfsi ones. I'd double check all the vac line and boost hoses as if it's kicking out black smoke it sounds like it's running very rich which would point towards a air leak.

[Cossie7]

I understand that mate but I've checked everything and also replaced hoses but what surely if it was a boost leak it would be there permanent? No fine one minute and leaking the next? Also when it does it it starts acting itself before it even builds boost? Ie at tick over?

Cheers

[Cossie7]

Sorry about the predictive text on this phone making my last post seem like it was written by an idiot lol

[Jaswan]

Did you do a proper pressurised leak test when you say you have checked for leaks or just had a look at all the connections etc?

If you haven't got the kit it only costs a few quid from a garage to get them to leak test it.

I understand what your saying about it being on and off though. Does the loom all look ok? I'm wondering if an injector is staying on or something.......

[Cossie7]

A did have a half shady pressure test done but I'm pretty sure it's not a boost leak as when it was running OK for that hour I'd didn't half get dome grief lol

I've had son thin similar a few times as I've had a load of red top turbos (vauxhall) and every time it was the temp sender for the ecu and this is behaving exactly like they did but I've changed it

Does any one know what the expected inlet air temp should be with a fully warmed up engine ie fan kicking on and off as well as ambient?

Cheers lads

[Error404]

This sounds like a fuelling issue, as above probably a boost / vac leak. They can be intermittent if it's a split under a clip or something, they can seal ok part of the time. First things first pull the fault codes otherwise you are just guessing.

[UrS4boy]

UrS C4, 200 20VT (3B) and S2/RS2 OBD1 Fault Code access port locations and info

We can't help you very well without some CEL/DTC codes that ECU will have, directing you (us too) towards the source of the problem.

Here is some reading for you:

UrS C4, 200 20VT (3B) and S2/RS2 OBD1 Fault Code access port locations and info:

http://forums.quattroworld.com/s4s6/msgs/90409.phtml

Help us help you.

[Cossie7]

Sort forgot to say plugged it in and only came up with g28 as usual and a lamba fault can't remember the code but just put it down to running so rich?

Cheers

[Error404]

Lambda codes normally means it's outside the mixture adaptation range therefore your AFRs are way off - 99% of the time this is a boost leak. You MUST do a thorough pressurised leak test.

[Cossie7]

Will do but would a boost leak effect tickover when hot but not effect it when it's driving?

I'm sorry but I don't understand how a boost leak would effect the car in heavy traffic at tick over but not under normal conditions?

But like I say I will have a full leak test done.
Cheers

[Cossie7]

Also just out of curiosity does everything look OK here?

[UrS4boy]

Sort forgot to say plugged it in and only came up with g28 as usual and a lamba fault can't remember the code but just put it down to running so rich?

Chicken/Egg.

We need to know what the code was that you saw, i.e. evidence in this cold case mystery.

[Cossie7]

Haha fair play I'm sure I will be able to get it again, probably within about 2 minutes of starting it tomorrow ��

[mike74]

MAF connnector. Unplug/connect umpteen times and see if its any different